Pueblo Bonito at Chaco Canyon National Historical Park in New Mexico. Because of the way that the first excavations of rooms at Pueblo Bonito were carried out a century ago, many of the questions that we have regarding the site now cannot be answered. During the 1990s, the GCI collaborated with the U.S. National Park Service to investigate, develop, and field-test, on a limited scale, several protective strategies for preserving the standing architectural remains at the site. Photo: Guillermo Aldana.